Friday afternoon’s downpour brought strong winds, lightning, and 1.5 inches of rain within an hour and a strong reminder of Pontiac’s recent bout of flooding issues.

It was already on the mind of Pontiac City Council members as Sewer Treatment Plant manager Todd Campbell brought back water concerns when requesting a new piece of equipment for the plant at Monday’s council meeting.

Campbell requested purchase of a gate valve at a cost of $11,040 to more effectively operate the gate, or entrance for sewage, when the Vermilion River reaches a high level. Campbell said the valve, that opens by lifting a round or rectangular gate/wedge out of the path of the fluid, could be operated manually, thereby giving staff better control in a situation such as the city experienced at the end of May.

The council approved the measure.

Campbell also noted that he has responded to the Illinois Environmental Protection Agency, which issued a non-compliance finding against the city for an emergency measure taken during the last week of May when Pontiac and surrounding areas experienced several periods of heavy rainfalls.

“We have five areas that are permitted combined sewer overflows, throughout the town, but mostly on the north side. Those are places where the storm drains are combined with sanitary sewers and high water levels will cause overflows. However, during the storms and heavy rainfall in May, we had overflow on the south side, in an unpermitted area, but we had to take action to keep the flooding (of basements) from getting worse,” he said.

Campbell made the decision to pump out a combined sewer system directly into the river to relieve the overwhelmed system. He did this after determining that what he was pumping over was pure rainwater.

“We could clearly tell it was rainwater, but it was against EPA regulations. I notified them immediately and they understood.”

“Our average flow here (at the treatment plant) is 2 million gallons of sewage water per day with a system designed for an average of 3.5 million gallons. It has a maximum capacity of 8.5 million gallons and can push 10 million, but that’s a lot. After the first heavy rain we had during that week in May, which came on the heels of a rainy week, we were at 10 million gallons.

“The inflow at the plant was still at capacity three days after it quit raining,” he added.

He noted that the circumstances were highly unusual in that there were basically two back-to-back flash floods.

The IEPA has requested a letter from the city explaining its actions and asking for corrective plans, which Campbell submitted. The EPA could close the matter, issue a reprimand or issue a fine. Campbell said he expects whatever action the EPA takes could come within a couple of weeks.

Page 2 of 3 - Pontiac has made strides in recent years to update its sewer system and put in separate storm drains.

“About 10 years ago, there were 330 inlets (street drains) that were tied into the sanitary sewer system. Once the project along North Street is complete, there will only be about 200 inlets left,” Campbell said. There remain about 110 inlets on the north side and 90 on the south side.

The EPA allows four permitted overflows in a year and since 2010, there have only been eight.

However, this year alone there have been 11 at one site, three each at two other sites and one at another site.

Because installing separate storm drains is costly, the city is only able to do large projects when grant money is made available, such as the $750,000 IKE grant to do this latest round, which will remove 41 inlets from the combined system.

City Administrator Bob Karls did note that other inlets are taken off on a smaller scale if an area is already undergoing street work.

The city has also installed nine pump stations throughout Pontiac, including Illini Subdivision and Fairway View, where land levels are too low for gravity flows to storm sewers. The pump stations literally pump water to an elevated level until gravity can take over and move the water along.

Water in the city’s storm sewers drain directly into the Vermilion River, while the sanitary sewer lines flow to the water treatment plant.

When the systems are combined and there’s heavy rain, it can overwhelm the treatment plant.

“Our two biggest issues are inflow and infiltration. Inflow is dealing with a lot of extra water, such as from the combined systems, where you have sewage and a lot of rain water. Not only the falling rain, but rain coming from roof gutters, footing tiles and sump pumps. It’s illegal to have a sump pump tied directly into the combined sewer systems. Homeowners should have them drain into a green space in their yards if they have them. I know at some point the yard can become so saturated it will just run off, but that’s how it overwhelms our systems.

New houses constructed now have to have sump pumps with injectors that drain to storm sewers. These pumps cut off back-flow into the basements. Karls said all new subdivisions have storm sewers as a requirement.

The sewer department also deals with infiltration issues, such as if a sewer line has a faulty joint, tree roots and other blocking debris.

“We’ve been sealing drains where possible, cleaning lines and cutting out roots. We’ve been replacing old brick manholes with new ones, but it is expensive and we can only do a few a year. The old brick manholes allow roots to easily infiltrate the sewer lines.”

Page 3 of 3 - “We’re doing what we can, but it is an expensive proposition. And unfortunately the plant itself is going to need updates soon. That will be expensive, too.”